16mm...good follicle size?

I went to my fertility specialist yesterday (CD 14) for an ultrasound. I also had a positive opk as well (first day). My doctor said I had one follicle and it was 16mm and that it wasn't that great of a size. They say anything 18mm and over is a good size. He also said that the follicles grow 1-2 mm a day. Yesterday I had a positive OPK and I took the test again today and it was positive again.....does this mean that my follicle could still be growing? Anyone got pregnant with a 16mm follicle. Thanks!!